000 AXNT20 KNHC 151042 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT FRI SEP 15 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURES... HURRICANE GORDON IS CENTERED NEAR 30.9N 53.4W AT 15/0900 UTC MOVING EAST-NORTHEAST AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 965 MB. MAXIMUM SUSTAINED WIND SPEED IS 95 KT WITH GUSTS TO 115 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. GORDON HAS BEGUN TO WEAKEN WITH THE EYE BECOMING SMALLER AND LESS DISTINCT. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90 NM FROM THE CENTER IN THE E SEMICIRCLE. SCATTERED MODERATE CONVECTION COVERS THE REMAINDER OF THE AREA FROM 29N-33N BETWEEN 50W-54W. TROPICAL STORM HELENE IS CENTERED NEAR 15.0N 40.3W AT 15/0900 MOVING WEST-NORTHWEST AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. HELENE CONTINUES TO MAINTAIN DEEP CONVECTION BUT IS NOW MOSTLY SW OF THE LOW LEVEL CENTER. SCATTERED MODERATE TO SCATTERED STRONG CONVECTION IS FROM 12N-16N BETWEEN 39W-43W. OUTER RAINBAND CONSISTING OF CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 45 NM OF LINE 18N38W-16N42W. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 60W S OF 15N MOVING W 10-15 KT. WEAK WAVE SIGNATURE IS OBSERVED AS THE WAVE APPROACHES THE LESSER ANTILLES. WAVE IS BENEATH THE W EDGE OF AN UPPER RIDGE AND A LARGE AREA OF VERY DRY AIR...THUS NO ASSOCIATED DEEP CONVECTION. TROPICAL WAVE IS ALONG 72W/73W S OF 19N MOVING W 15 KT. BROAD WELL-DEFINED LOW LEVEL INVERTED-V SATELLITE SIGNATURE IS OBSERVED OVER THE CENTRAL CARIBBEAN. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 16N TO THE COAST OF HISPANIOLA BETWEEN 69W-73W. TROPICAL WAVE IS ALONG 82W S OF 17N MOVING W 15 KT. WEAK LOW LEVEL INVERTED-V SATELLITE SIGNATURE IS OBSERVED OVER THE W CARIBBEAN. WAVE IS EMBEDDED WITHIN DRY AIR THUS ONLY ISOLATED SHOWERS ARE WITHIN 45 NM OF LINE FROM 20N76W-17N81W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 15N16W 13N26W 15N35W THEN ALONG 9N42W 7N51W INTO THE CARIBBEAN ALONG 11N66W ACROSS THE N PORTION OF SOUTH AMERICA AND PANAMA INTO THE E PACIFIC REGION NEAR 10N82W. SCATTERED STRONG CONVECTION IS WITHIN 150 NM N OF THE AXIS E OF 18W TO INLAND OVER AFRICA. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 120/150 NM OF THE AXIS FROM 18W-23W AND WITHIN 120 NM OF THE AXIS FROM 32W-36W. ...DISCUSSION... GULF OF MEXICO... BROAD DEEP LAYERED TROUGH COVERS THE E US...THE W ATLC AND THE N GULF COAST ANCHORED BY AN UPPER LOW MOVING ACROSS NEW ENGLAND. ASSOCIATED FRONTAL BOUNDARY EXTENDS INTO THE GULF FROM THE W ATLC ACROSS THE FLORIDA PENINSULA NEAR FT. MYERS WHERE IT BECOMING A SURFACE TROUGH ACROSS THE GULF TO OFF THE CENTRAL TEXAS COAST. ISOLATED SHOWERS ARE OVER THE N GULF FROM 24N-28N BETWEEN 86W-95W. UPPER RIDGE EXTENDS ACROSS THE REMAINDER OF THE GULF ANCHORED BY AN UPPER HIGH ASSOCIATED WITH A TROPICAL STORM OFF THE W COAST OF MEXICO ENTERING THE GULF NEAR TAMPICO MEXICO INTO THE W ATLC OVER THE FLORIDA KEYS/STRAITS OF FLORIDA. ISOLATED SHOWERS ARE FROM 23N-25N E OF 83W TO THROUGH THE STRAITS OF FLORIDA AND S OF 24N W OF 95W TO INLAND OVER MEXICO. CARIBBEAN SEA... W CARIBBEAN IS DOMINATED BY NE UPPER FLOW FROM THE UPPER RIDGE THAT EXTENDS ACROSS THE GULF OF MEXICO INTO THE W ATLC. THIS IS PROVIDING DRY AIR ACROSS THE AREA INCLUDING THE TROPICAL WAVE ALONG 81W. NARROWING UPPER TROUGH EXTENDS ACROSS FROM HAITI/E CUBA SW TO CENTRAL NICARAGUA. AN UPPER HIGH IS LOCATED OVER SOUTH AMERICA WITH A RIDGE EXTENDING N INTO THE CENTRAL CARIBBEAN S OF 16N FROM 68W-80W. REMAINDER OF THE CARIBBEAN IS DOMINATED BY S UPPER FLOW FROM AN UPPER RIDGE ANCHORED IN THE TROPICAL/CENTRAL ATLC GENERATING SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 90 NM OF LINE 11N62W-15N67W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 10-14N BETWEEN 76W-83W IN ASSOCIATION WITH THE ITCZ ACROSS THE AREA. ATLANTIC OCEAN... BROAD DEEP LAYERED TROUGH THAT COVERS THE E US AND THE N GULF EXTENDS INTO THE W ATLC IS ANCHORED BY AN UPPER LOW MOVING ACROSS NEW ENGLAND. THE ASSOCIATED FRONTAL BOUNDARY EXTENDS INTO THE W ATLC FROM A 1010 MB LOW OFF NORTH CAROLINA COAST THROUGH 32N76W INTO THE GULF NEAR WEST PALM BEACH GIVING THE AREA SCATTERED MODERATE/ISOLATED STRONG CONVECTION E OF THE FRONT WITHIN 75 NM OF LINE FROM 28N77W TO BEYOND 32N74W. SURFACE TROUGH IS TO THE E OF THE FRONT EXTENDING THROUGH 32N69W TO THE CENTRAL BAHAMAS NEAR 23N74W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120 NM E OF OF SURFACE TROUGH. UPPER RIDGE AXIS EXTENDS FROM THE GULF OF MEXICO INTO THE W ATLC ACROSS THE FLORIDA KEYS/STRAITS OF FLORIDA NE TO NEAR 30N70W. NARROW UPPER TROUGH EXTENDS ACROSS HAITI/E CUBA INTO THE W ATLC TO NEAR 25N69W. BROAD UPPER RIDGE COVERS THE W/CENTRAL AND TROPICAL ATLC ANCHORED NEAR 21N57W COVERING THE AREA S OF 28N FROM 50W-68W. TROPICAL MOISTURE IS BEING DRAWN N OF THE E CARIBBEAN AND WITH SUFFICIENT DIFFLUENCE TO GENERATE AN AREA OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 18N-24N BETWEEN 61W-68W. GORDON IS N OF THIS UPPER RIDGE. AN UPPER RIDGE COVERS THE REMAINDER OF THE E ATLC E OF 30W ANCHORED NEAR 30N24W EXTENDING E TO OVER THE CANARY ISLANDS. AN UPPER HIGH ASSOCIATED WITH TROPICAL STORM HELENE COVERS THE SE TROPICAL ATLC WITH A SMALL UPPER LOW JUST TO THE E CENTERED N OF THE CAPE VERDE ISLANDS NEAR 20N25W. THE SUBTROPICAL RIDGE IS ONCE AGAIN SPREADING W OVER THE ATLC IN SPITE OF THE PRESENCE OF HURRICANE GORDON WITH A 1026 MB HIGH OVER THE S MOST ISLANDS OF THE AZORES. THE FIRST VISIBLE SATELLITE IMAGES THIS MORNING SHOWS A LARGE AREA OF AFRICA DUST FROM THE ITCZ TO 27N BETWEEN 44W-64W INCLUDING THE FAR E CARIBBEAN WITH HELENE JUST TO THE E OF THE DUST AND YET ANOTHER AREA OF AFRICAN DUST MOVING OFF AFRICA FROM 13N-22N FROM OVER THE CAPE VERDE ISLANDS TO THE COAST OF AFRICA. $$ WALLACE